Paleomagnetism of parts of the Late Triassic diabase dike system associated with the trans-New Brunswick aeromagnetic lineament

1981 ◽  
Vol 18 (12) ◽  
pp. 1776-1787 ◽  
Author(s):  
M. K. Seguin ◽  
K. V. Rao ◽  
D. V. Venugopal ◽  
E. Gahe
Keyword(s):  
New Brunswick ◽  
Middle Jurassic ◽  
Late Jurassic ◽  
The Other ◽  
Late Triassic ◽  
General Area ◽  
Present Stage ◽  
Paleomagnetic Study ◽  
C And N ◽  
Radiometric Data

A paleomagnetic study was conducted on dike samples taken from three widely separated localities along the northeasterly trending Caraquet dike system (New Brunswick) in order to define their age relationship. This dike system is recognized on the basis of a well defined aeromagnetic lineament. Stable magnetization directions were isolated after alternating field (15–40 mT) and thermal (300–550 °C) treatments of the samples taken from the three localities: C (353°, +56°), N (353°, +50°), and T (14°, +37°). The virtual pole derived from dike T (82°E, 62°N) agrees well with previously determined Late Triassic – Early Jurassic (200–190 Ma) poles for the Appalachians. On the other hand, the other two virtual pole positions from dikes C (143°E, 78°N) and N (133°E, 74°N) fall in the general area of average paleopoles for the Middle–Late Jurassic (180–170 Ma) age. The possibility that the dike at T differs in age from that of the dikes at localities C and N by at least 20 Ma is suggested. In the absence of reliable radiometric data, it is premature at the present stage to predict a likely occurrence of "younger" magnetization in these dikes related in origin to viscous partial thermoremanence possibly associated with the rifting and opening of the Atlantic in Middle Jurassic. Further investigations on newly found diabase outcrops along the magnetic lineament are in progress.

scholarly journals A new stem turtle from the Middle Jurassic of Scotland: new insights into the evolution and palaeoecology of basal turtles

2008 ◽  
Vol 276 (1658) ◽  
pp. 879-886 ◽  
Author(s):  
Jérémy Anquetin ◽  
Paul M Barrett ◽  
Marc E.H Jones ◽  
Scott Moore-Fay ◽  
Susan E Evans
Keyword(s):  
Middle Jurassic ◽  
Late Jurassic ◽  
Evolutionary History ◽  
Sister Group ◽  
Late Triassic ◽  
Sister Group Relationship ◽  
New Taxon ◽  
Crown Group ◽  
History Of ◽  
Isle Of Skye

The discovery of a new stem turtle from the Middle Jurassic (Bathonian) deposits of the Isle of Skye, Scotland, sheds new light on the early evolutionary history of Testudinata. Eileanchelys waldmani gen. et sp. nov. is known from cranial and postcranial material of several individuals and represents the most complete Middle Jurassic turtle described to date, bridging the morphological gap between basal turtles from the Late Triassic–Early Jurassic and crown-group turtles that diversify during the Late Jurassic. A phylogenetic analysis places the new taxon within the stem group of Testudines (crown-group turtles) and suggests a sister-group relationship between E. waldmani and Heckerochelys romani from the Middle Jurassic of Russia. Moreover, E. waldmani also demonstrates that stem turtles were ecologically diverse, as it may represent the earliest known aquatic turtle.

scholarly journals Mesozoic Intracontinental Orogeny in the Tectonic History of the Kolyvan’– Tomsk Folded Zone (Southern Siberia): a Synthesis of Geological Data and results of Apatite Fission Track Analysis

2021 ◽  
Vol 62 (9) ◽  
pp. 1006-1020
Author(s):  
F.I. Zhimulev ◽  
E.V. Vetrov ◽  
I.S. Novikov ◽  
G. Van Ranst ◽  
S. Nachtergaele ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
Middle Jurassic ◽  
Late Jurassic ◽  
Fission Track ◽  
Early Jurassic ◽  
Late Triassic ◽  
Apatite Fission Track ◽  
History Of ◽  
Paleozoic Rocks ◽  
Orogenic Events

Abstract —The Kolyvan’–Tomsk folded zone (KTFZ) is a late Permian collisional orogen in the northwestern section of the Central Asian Orogenic Belt. The Mesozoic history of the KTFZ area includes Late Triassic–Early Jurassic and Late Jurassic–Early Cretaceous orogenic events. The earlier event produced narrow deep half-ramp basins filled with Early–Middle Jurassic molasse south of the KTFZ, and the later activity rejuvenated the Tomsk thrust fault, whereby the KTFZ Paleozoic rocks were thrust over the Early–Middle Jurassic basin sediments. The Mesozoic orogenic events induced erosion and the ensuing exposure of granitoids (Barlak complex) that were emplaced in a within-plate context after the Permian collisional orogeny. Both events were most likely associated with ocean closure, i.e., the Paleothetys Ocean in the Late Triassic–Early Jurassic and the Mongol–Okhotsk Ocean in the Late Jurassic–Early Cretaceous. The apatite fission track (AFT) ages of granitoids from the Ob’ complex in the KTFZ range between ~120 and 100 Ma (the Aptian and the Albian). The rocks with Early Cretaceous AFT ages were exhumed as a result of denudation and peneplanation of the Early Cretaceous orogeny, which produced a vast Late Cretaceous–Paleogene planation surface. The tectonic pattern of the two orogenic events, although being different in details, generally inherited the late Paleozoic primary collisional structure of the Kolyvan’–Tomsk zone.

THE HUTTON SANDSTONE - TWO SEPARATE RESERVOIRS IN THE EROMANGA BASIN, SOUTH AUSTRALIA

1983 ◽  
Vol 23 (1) ◽  
pp. 109 ◽  
Author(s):  
D. Gravestock ◽  
M. Griffiths ◽  
A. Hill
Keyword(s):  
Middle Jurassic ◽  
Late Jurassic ◽  
South Australia ◽  
The Other ◽  
The South ◽  
Humid Climate ◽  
Trap Potential ◽  
Basin Margin ◽  
Eromanga Basin

The Hutton Sandstone in the South Australian portion of the Eromanga Basin consists of two units, one Early to Middle Jurassic, the other Middle to Late Jurassic in age. The younger unit may conformably overlie the older in areas of persistent subsidence but either may be thin or absent in areas of complex structure.Siliceous and calcareous authigenic cements at the top of the older unit and within the younger unit indicate surficial weathering in a warm arid to humid climate, supported independently by palaeofloral and faunal evidence. Duricrusts of Middle to Late Jurassic age have been recorded in outcrop from the southwest Eromanga Basin margin and the Surat Basin region.Both units have disconformity trap potential and the younger unit has additional poor to excellent stratigraphic trap potential. Exploration strategies will be enhanced by mapping each unit as a separate reservoir and by recognizing the downflank stratigraphic trap potential of the younger unit.

Reappraisal of the Mesozoic tectonic transition from the Paleo-Tethyan to Paleo-Pacific domains in South China

2021 ◽  
Author(s):  
Chengshi Gan ◽  
Yuzhi Zhang ◽  
Yuejun Wang ◽  
Xin Qian ◽  
Yang Wang
Keyword(s):  
South China ◽  
Middle Jurassic ◽  
Late Jurassic ◽  
Sedimentary Rocks ◽  
Early Jurassic ◽  
Igneous Rocks ◽  
Late Triassic ◽  
Geochemical Data ◽  
South China Block ◽  
Tectonic Transition

The southeastern (SE) South China Block was mainly influenced by the Paleo-Tethyan and Paleo-Pacific dynamic domains during the Mesozoic. The initial timing of the tectonic transition between these two domains in the SE South China Block still remains debated. The transition would affect the nature of the lithosphere and material provenance of sediments, and, therefore, igneous and sedimentary rocks in the area could record such dynamic processes. In this study, published geochronological and geochemical data of the Triassic and Jurassic igneous rocks and detrital zircon data of contemporaneous sedimentary rocks in the SE South China Block were compiled, aiming to provide constraints on the tectonic transition via tracing the spatial-temporal variations in the nature of the lithosphere and sedimentary provenance signals. The compiled results suggest that the magmatic intensity and volume decreased significantly from the Late Triassic to Early−Middle Jurassic, with an obvious magmatic quiescence between them, and increased from the Early−Middle Jurassic to Late Jurassic. The εNd(t) and zircon εHf(t) values of mafic rocks, granitoids, and shoshonitic rocks remarkably increased from the Late Triassic to Early−Middle Jurassic, indicative of variations in the lithospheric mantle and continental crust. Such variations suggest that the initial tectonic transition occurred at the earliest Early Jurassic. Based on the southward paleocurrents from Early Jurassic sandstone, E-W−trending extension of Early−Middle Jurassic mafic and shoshonitic rocks, and similar sedimentary provenances of Late Triassic and Early−Middle Jurassic sedimentary rocks, these features imply that the SE South China Block was not immediately influenced by the Paleo-Pacific domain during the Early−Middle Jurassic. However, from the Early−Middle Jurassic to Late Jurassic and Early Cretaceous, the spatial distribution, geochemical signatures, magmatic intensity, and magmatic volume of igneous rocks and provenance of sedimentary rocks exhibit obvious variations, and the regional fold hinge direction changed from E-W−trending to NE-trending, suggesting significant effects from Paleo-Pacific subduction on the SE South China Block. Thus, the Mesozoic tectonic transition from the Paleo-Tethyan to the Paleo-Pacific dynamic domain in the SE South China Block likely occurred during the Early−Middle Jurassic.

The role of Central Asia in dinosaurian biogeography

1993 ◽  
Vol 30 (10) ◽  
pp. 2002-2012 ◽  
Author(s):  
Dale A. Russell
Keyword(s):  
North America ◽  
Central Asia ◽  
Early Cretaceous ◽  
Late Cretaceous ◽  
Middle Jurassic ◽  
Late Jurassic ◽  
Late Triassic ◽  
Globally Distributed ◽  
Northern And Southern Hemispheres

Dinosaurian biogeography may have been largely controlled by the Mesozoic fragmentation of Pangea and the reassembly of its fragments into a new, boreal supercontinent (Laurasia). Although Late Triassic and Early Jurassic dinosaurs were globally distributed, Chinese assemblages were dominated by endemic forms from Middle Jurassic into Early Cretaceous time. The affinities of Aptian – Albian immigrants to Asia were strongest with North America and Europe rather than Gondwana, indicating that the northern and southern hemispheres had by then attained their biogeographic identity. This distinctiveness was maintained through Cretaceous time. Europe seems to have been a buffer area between Paleolaurasia and Gondwana; of the northern continents it was the most strongly influenced by Gondwana dispersants. Late Jurassic dinosaur assemblages in North America exhibited Gondwana affinities, but by Late Cretaceous time they were dominated by forms of Asian ancestry.

First rove beetles from the Jurassic Talbragar Fish Bed of Australia (Coleoptera, Staphylinidae)

2013 ◽  
Vol 87 (4) ◽  
pp. 650-656 ◽  
Author(s):  
Chen-Yang Cai ◽  
Evgeny V. Yan ◽  
Robert Beattie ◽  
Bo Wang ◽  
Di-Ying Huang
Keyword(s):  
Middle Jurassic ◽  
Fossil Record ◽  
Late Jurassic ◽  
New South ◽  
New South Wales ◽  
The Other ◽  
Rove Beetles ◽  
Rove Beetle ◽  
South Wales ◽  
Distinct Features

The first two rove beetle fossils discovered from the Late Jurassic Talbragar Fish Bed in New South Wales, Australia are described and illustrated.Juroglypholoma talbragarensen. sp. is the second fossil record for one of the smallest and latest recognized staphylinid subfamily Glypholomatinae. The other staphylinid,Protachinus minorn. gen. n. sp., is an unusual member of extant subfamily Tachyporinae (tribe Tachyporini). It significantly retains several distinct features, including entire epistomal suture, and abdominal tergites III–VI each with a pair of basolateral ridges. The discovery of a new glypholomatine in Australia, together with recently reported one from the Middle Jurassic Daohugou biota of China, suggests the subfamily Glypholomatinae was probably much more widespread in the Jurassic than previously thought.

Middle Jurassic turtles from the Sichuan Basin, China: a review

2011 ◽  
Vol 149 (4) ◽  
pp. 675-695 ◽  
Author(s):  
HAIYAN TONG ◽  
IGOR DANILOV ◽  
YONG YE ◽  
HUI OUYANG ◽  
GUANGZHAO PENG
Keyword(s):  
Middle Jurassic ◽  
Sichuan Basin ◽  
Late Jurassic ◽  
Upper Jurassic ◽  
The Other ◽  
Dominant Group ◽  
Genus Level ◽  
The Family ◽  
The Sichuan Basin ◽  
The One

AbstractThe turtle fauna of the Middle Jurassic Xiashaximiao Formation in the Sichuan Basin and the type series ofChengyuchelys baenoidesYoung & Chow, 1953 are revised. By the absence of a mesoplastron and other shell characters, both the holotype and paratype ofChengyuchelys baenoidesbelong to the family Xinjiangchelyidae and come probably from the Upper Jurassic Shangshaximiao Formation. The Middle Jurassic turtle assemblage of the Sichuan Basin is composed of two entities: the Bashuchelyidae fam. nov. (Bashuchelysgen. nov.,Chuannanchelysgen. nov.) andProtoxinjiangchelysgen. nov. on the one hand, andSichuanchelyson the other hand, with the former as the dominant group. Bashuchelyids and xinjiangchelyids are closely related to one another, whileSichuanchelysis more primitive and has no shared apomorphic features with bashuchelyids. The whole assemblage appears to be endemic to the Sichuan Basin at genus level and distinct from the Late Jurassic turtle fauna of the same basin in its relict nature and absence of the Polycryptodira.

The Canadian Cordillera, the Hellenides, and the Sea-Floor Spreading Theory

1972 ◽  
Vol 9 (6) ◽  
pp. 709-743 ◽  
Author(s):  
Jean Dercourt
Keyword(s):  
Pacific Ocean ◽  
Oceanic Crust ◽  
Continental Margin ◽  
Middle Jurassic ◽  
Late Jurassic ◽  
Late Triassic ◽  
Canadian Cordillera ◽  
Transform Faults ◽  
Sea Floor ◽  
Sea Floor Spreading

The theory of plate tectonics is applied to the tectonic evolution of the Hellenides and the Canadian Cordillera. In the Hellenides a Tethyan zone of sea-floor spreading developed within the continental crust during Triassic time and functioned until the end of the Middle Jurassic. It led to the formation of two plates, each with continental and oceanic segments, that were separated in some places by accreting plate margins and in others by transform faults. In Late Jurassic time the mid-Tethyan ridge became inactive as new ridges developed in the Atlantic Ocean. From Late Jurassic to Recent time, Tethyan oceanic crust largely disappeared under one of the cratons. The chronology of tectonic events in the Hellenides corresponds well with that of sea-floor spreading in the Atlantic.Four periods of sea-floor spreading were involved in the formation of the Canadian Cordillera: (1) a Silurian? to Early Devonian period when an Archeo-Pacific Ocean separated the Canadian craton with a stable sedimentary margin from a volcanic archipelago; (2) a Middle Devonian to Permian period when the extinct volcanic archipelago was bounded to the west by a spreading Paleo-Pacific Ocean, and to the east by a tectonic contact which was consuming Archeo-Pacific oceanic crust; part of this crust was obducted over the continental margin; (3) a Late Triassic to Middle Jurassic period when a second volcanic archipelago separated a spreading Neo-Pacific Ocean from the continental margin; and (4) a Late Jurassic to Recent period where spreading occurred in both the Atlantic and Pacific Oceans, subjecting the second volcanic archipelago and the continental margin to major tectonism; since the Paleocene, the Cordillera has slid towards the NNW along transform faults.

scholarly journals A new stem turtle from the Middle Jurassic of Scotland: new insights into the evolution and palaeoecology of basal turtles

2017 ◽  
Author(s):  
Jérémy Anquetin ◽  
Paul M. Barrett ◽  
Marc E. H. Jones ◽  
Scott Moore-Fay ◽  
Susan E. Evans
Keyword(s):  
Middle Jurassic ◽  
Late Jurassic ◽  
Evolutionary History ◽  
Sister Group ◽  
Late Triassic ◽  
Sister Group Relationship ◽  
New Taxon ◽  
Crown Group ◽  
History Of ◽  
Isle Of Skye

The discovery of a new stem turtle from the Middle Jurassic (Bathonian) deposits of the Isle of Skye, Scotland, sheds new light on the early evolutionary history of Testudinata. Eileanchelys waldmani gen. et sp. nov. is known from cranial and postcranial material of several individuals and represents the most complete Middle Jurassic turtle described to date, bridging the morphological gap between basal turtles from the Late Triassic–Early Jurassic and crown-group turtles that diversify during the Late Jurassic. A phylogenetic analysis places the new taxon within the stem group of Testudines (crown-group turtles) and suggests a sister-group relationship between E. waldmani and Heckerochelys romani from the Middle Jurassic of Russia. Moreover, E. waldmani also demonstrates that stem turtles were ecologically diverse, as it may represent the earliest known aquatic turtle.

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